直喷汽油机喷嘴积碳对喷雾的影响

Effect of GDI Engine Injector Coking on Spray

利用纹影法,在定容燃烧弹中对直喷汽油机喷油器进行喷雾特性试验,对比了未积碳喷油器、积碳喷油器和物理清洗过的积碳喷油器在不同喷射压力下的喷雾形态、喷雾锥角以及贯穿距离.结果表明:积碳后喷油器雾化质量较差,喷雾锥角和贯穿距离明显小于未积碳喷油器的喷雾锥角和贯穿距离,提高喷射压力后这种差距有所缩小;积碳喷油器单束油束贯穿距离差别较大,积碳后喷油器流量显著降低,且随喷油压力的增加,积碳喷油器流量的变化更为显著;扫描电子显微镜显示喷油器各喷孔积碳程度不一致,经X射线能谱分析检测后发现,机油中的某些成分以及摩擦产生的金属碎屑对积碳的形成起到促进作用.

By means of schlieren method,spray characteristics text was conducted on a gasoline direct injec-tion（GDI）engine injector in a constant volume combustion bomb. The spray patterns,spray angle and penetration distance under different injection pressures were compared among new injector,coking injector,and rinsedcoking injector. The results revealed that coking injector had a poorer atomization effect as well as a significantly smaller spray angle and penetration distance,but these problems could be improved by increasing the injection pressure. In comparison with the new injector,the penetration distance of the sprays from coking injector varied greatly. Addi-tionally,the flow of fuel injector was obviously reduced after coking and presented a more significant difference from new injector when injection pressure increased. Scanning electron microscopy images showed that orifices of injector were coked in different degrees. An X-ray spectroscopy analysis also indicated that some ingredients in the oil and metal debris generated by friction played an important role in promoting the formation of coke.